How to call an express export method internally? - javascript

This is my first method that responds well to an http call:
exports.create = function(req, res, next){
var submission = new task(req.body);
submission.save(function(err){
if(err){
return next(err);
} else {
res.json(submission);
}
});
};
Now, I want to call this from a method defined in the same file:
exports.evaluate = function(req, res, next){
if(req.body.value == x){
// need to call the above method
this.create(req.body.someobject)
}
};
How can this be done?

The right way to do this is to define a common method which isn't a route handler and call it from the handlers.
var _create = function (object, callback) {
var submission = new task (object);
submission.save(callback);
}
exports.create = function(req, res, next){
_create(req.body, function(err){
if(err){
return next(err);
} else {
res.json(submission);
}
});
};
exports.evaluate = function(req, res, next){
if(req.body.value == x){
// need to call the above method
_create(req.body.someobject, function (err) {
// Send response
});
}
};

Related

Pass Parameter to Function Express JS

everything good ? I would like to know the best way and if it is possible to send a certain parameter to an express function in the NodeJS.
i wanna pass the string ('admin') or other string that i want to function 'RoleTolen', using my route.
function verifyToken
function verifyToken(req, res, next) {
// Get auth header value
const bearerHeader = req.headers["authorization"];
// Check if bearer is undefined
if (typeof bearerHeader !== "undefined") {
// Split at the space
const bearer = bearerHeader.split(" ");
// Get token from array
const bearerToken = bearer[1];
// Set the token
req.token = bearerToken;
// Next middleware
next();
} else {
// Forbidden
res.sendStatus(403);
}
}
function ValidToken
function validToken(req, res, next) {
jwt.verify(req.token, process.env.SECRET, (err, authData) => {
if (err) {
res.sendStatus(403);
} else {
next();
}
});
}
function RolesToken
function rolesToken(role, req, res, next) {
var decoded = jwt.decode(req.token);
if (!decoded.permissions.includes(role)) {
res.json("sem permissao");
} else {
next();
}
}
my route
router.post(
"/posts",
verifyToken,
validToken,
rolesToken("admin"),
customerController.posts
);
function rolesToken(role, req, res, next) is not a proper Express.js route handler, as you already know (and hence the question, I assume).
What you can do is to write your rolesToken as a function that returns the actual Express.js compliant handler (function):
function rolesToken(role) {
return function(req, res, next) {
var decoded = jwt.decode(req.token);
if (!decoded.permissions.includes(role)) {
res.json("sem permissao");
} else {
next();
}
};
}
from the docs
Define error-handling middleware functions in the same way as other middleware functions, except with four arguments instead of three, specifically with the signature (err, req, res, next)):
Therefore your RolesTaken function won't work as expected.
Secondly, you can create a middleware or modify existing one
(req, res, next) => {
//some stuff
if(req.path == '/posts') req.role= 'admin';
if(req.path == '/someOtherPath') req.role= 'someRole';
//some other stuff
}
Now you can get the get the role in req.someProp in the your controller middlerware as req.role
you would like to see this question also

Need a way to set res object after couchbase DB call "Error: Can't set headers after they are sent"

var express = require('express');
var search = express.Router();
search.get('/', function(req, res, next) {
console.log('1');
dbCall(function(error, result) {
if (error) {
res.status(404).json();
} else {
res.json(result);
}
});
console.log('last');
next();
});
var dbCall = function(callback) {
var couchbase = require('couchbase');
var cluster = new couchbase.Cluster('couchbase://127.0.0.1');
var bucket = cluster.openBucket('default');
var doc;
var ViewQuery = couchbase.ViewQuery;
var query = ViewQuery.from('dev_test', 'allData');
bucket.query(query, function(err, viewResults) {
if (err) {
callback(err, null);
} else {
console.log('inqueryCall');
var results = viewResults;
callback(null, results);
console.log(results);
}
});
};
module.exports = search;
Here's the error that I get is :
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:346:11)
Can someone please explain the issue here(not just the solution)?
I've added console.log and the issue here is that the couchbase call to async
Remove next() call, that is causing this error. next() is used in middleware to pass the flow to next middleware or endpoint/route
search.get('/', function(req, res, next) {
dbCall(function(error, result) {
if (error) {
res.status(404).json();
} else {
res.json(result);
}
});
});

Remove a field of my json in a specific case

I have an ExpressJS controller that list all my users
userCtrl.get :
get(req, res, next) {
var func = function(err, data) {
if (err) return next(err);
return res.json(data);
};
if (req.params[this.idName])
this._getById(req.params[this.idName], func);
else
this._getAll(func);
}
_getById(id, fn) {
this.ObjectClass.findById(id, fn);
}
_getAll(fn) {
this.ObjectClass.findAll(fn);
}
I'd like to call it from another road, in such a way that res.json() will filter a field of this json
Something like :
router.get ('/services/:serviceKey/authBridge/users', function(req, res, next) {
function anonJs(x) {
x.forEach(s => s.credential = null);
res.json(x);
}
res.json = anonJs;
userCtrl.get(req, res, next);
});
The problem is, with this last piece of code I end up with a recursion as I call res.json that is now defined as anonJS
You must store the reference to the old function before replacing it.
router.get ('/services/:serviceKey/authBridge/users', function(req, res, next) {
var json = res.json;
res.json = function(x) {
x.forEach(s => s.credential = null);
json(x);
}
userCtrl.get(req, res, next);
});

Node.js async consistency

I have the following code :
server.use(function(req, res, next) {
users_db.set(req.user, function(err) { // async call to mongodb
if (err) {
console.error(err);
}
});
}
return next();
});
server.get('/', function(req, res) {
req.user.active = true; // this is a new field in user object
res.send(req.user);
}
});
So, As you see, when users_db.set() is called, req.user doesn't have the active=true field. It is being inserted only in the server.get() function.
Is it possible that user.active = true is registered in the db nevertheless because of the asynchronous nature of the call ?
As far as I know (it is like that in Express at least) .get method accepts many middleware functions. So I guess that the following will work:
server.get(
'/',
function(req, res, next) {
req.user.active = true; // this is a new field in user object
res.send(req.user);
next();
},
function(req, res, next) {
users_db.set(req.user, function(err) { // async call to mongodb
if (err) {
console.error(err);
}
});
}
return next();
}
);
Doing the things like that you are sure that req.user.active is populated always before to reach the moment with users_db.set.

exit from chain of route specific middleware in express/ nodejs

I have a chain of "route specific middleware" for this route, like so:
var express = require('express');
var server = express();
var mw1 = function(req, resp, next) {
//do stuff
if (success) {
next();
} else {
req.connection.destroy(); //without calling next()
}
};
var mw2 = function(req, resp, next) {
//do stuff
if (success) {
next();
} else {
req.connection.destroy(); //without calling next()
}
};
server.post('/some/path', [mw1, mw2], function(req, resp) {
//write response
});
[mw1, mw2] are the middleware specific to the route /some/path.
This is different from server-wide middleware like this:
server.use(mw1);
server.use(mw2);
Where it applies to all routes defined.
Now my issue is that I want to exit from the chain. I.e. if success is false in mw1, I do not wish for mw2 to be called. If success is false in mw2, I do not without for the route function to be called. Presently, both mw1 and mw2 appear to be getting called whether or not next() is called - and I do not know why.
How can I go about doing this?
You can call next( 'route' ), as said on the express api reference, application routing section:
Multiple callbacks may be given, all are treated equally, and behave
just like middleware, with the one exception that these callbacks may
invoke next('route') to bypass the remaining route callback(s).
Example
var express = require('express')
, app = express()
;
// keep an eye on the function names
app.post( '/some/path', middleware1, middleware2, function route1( req, res, next ) {
// write response
});
app.all( '*', function route2( req, res, next ) {
// do something like handle a 404 request
});
app.use(function errorHandler( err, req, res, next ) {
// handle error
});
function middleware1( req, res, next ) {
// ...
if ( !success ) {
// bypasses middleware2 and route1, route2 will be called
return next( 'route' );
}
// calls middleware2
next();
}
// intentionally similar to middleware1 to keep things clear
function middleware2( req, res, next ) {
if ( !success ) {
// bypasses route1 and route2
// errorHandler will be called with the error
return next( Error( 'middleware 2 failed' ) );
}
// calls route1
next();
}
A little more tinkering yielded the answer:
var express = require('express');
var server = express();
var mw1 = function(req, resp, next) {
//do stuff
if (success) {
next();
} else {
resp.send(406, 'Invalid because of this');
req.connection.destroy(); //without calling next()
}
};
var mw2 = function(req, resp, next) {
//do stuff
if (success) {
next();
} else {
resp.send(406, 'Invalid because of that');
req.connection.destroy(); //without calling next()
}
};
server.post('/some/path', [mw1, mw2], function(req, resp) {
//write response
});
The trick was send a response: resp.send(406, 'Invalid because of this');
Just prior to destroying the connection: req.connection.destroy();
In fact not destroying the connection, I found to also work, in the general case.
(But was required in my specific case, and is out of the scope of this question.)
If the response has already been sent, then express does not automatically call next() for you, as it appeared to do otherwise.
I was under the impression that if you neither call next() nor send a response in a route handling function, express just hangs. Also FWIW I haven't used an array, mine looks like server.post('/some/path', mw1, mw2, function(req, resp) {...
Anyway. One alternative might be to restructure your code so you only have a single handling function. Do you have a good reason for mw1 and mw2 being middleware instead of regular async functions your handler calls?
var express = require('express');
var server = express();
var mw1 = function(req, res, callback) {
// do stuff with req/res if necessary but don't send a response
if (success) {
callback(null);
} else {
callback('Error');
}
};
var mw2 = function(req, res, callback) {
//do other stuff but don't send a response
if (success) {
callback(null);
} else {
callback('Error');
}
};
function mwBoth(req, res){
mw1(req, res, function(err){
if(err){ return res.send(500) };
mw2(req, res, function(err){
if(err){ return res.send(500) };
// neither had an error
res.redirect('/some/other/path');
});
});
};
server.post('/some/path', mwBoth);

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